During stitching operation of the sewing machine, especially pattern stitching or embroidery stitching, for example, a plurality of threads of different colors are prepared, and when a color of an upper thread is changed during operation, it is necessary to lift up a presser foot, cut the upper thread, remove it from the sewing machine, set an upper thread of a different color to the sewing machine, and pass it through thread guides, a thread tension, a take-up lever and others. Such a sequential process is troublesome, and if the colored threads are often changed, a great deal of time is taken up therefor.
As another example, in machines, e.g., an embroidery machine which uses various kinds of colored threads, many needle bars are in advance set with threads of different colors to be selected and changed.